半连续浇铸AZ61合金中枝晶形貌特性  

Morphology Features of Dendrite in Semi-Continuously Cast AZ61 Alloy

作　　者：冯中学[1] 潘复生[2] 史庆南[1] 张喜燕[2] 陈亮维[1] 陈希亮[1] 

机构地区：[1]昆明理工大学,云南昆明650000 [2]重庆大学国家镁合金材料工程技术研究中心,重庆400044

出　　处：《稀有金属材料与工程》2014年第4期995-998,共4页Rare Metal Materials and Engineering

基　　金：国家自然科学基金项目(50725413;50890170;51071183);国家重大基础研究项目("973")(2007CB613704);重庆市科委项目(2010CSTC-HDLS)

摘　　要：采用彩色金相与能谱对半连续浇铸的AZ61镁合金进行了组织和成分上的观察,发现冷却速率较快的铸锭边部的二次枝晶间距比冷却速率较慢的铸锭心部的二次枝晶间距大,与普通模铸的显微组织呈现的规律不同,并对这一现象进行了理论上的分析讨论。分析认为边部二次枝晶间距的异常增大与二次枝晶臂表面溶质的微观偏析密切相关,粗枝晶臂表面溶质浓度与细枝晶臂表面溶质浓度差值越大,粗枝晶臂的粗化驱动能越大,枝晶的二次枝晶间距就越大。The microstructure and composition of the semi-continuously cast AZ61 alloy has been analyzed by color metallography and Energy Dispersive X-ray Detector （EDX）. The unusual phenomenon has been found that the secondary dendrite arm spacing （SDAS） in the edge of the casting with higher cooling rate is wider than the SDAS of the center of the casting. This tendency is different from the orthodox casting. The phenomenon has been analyzed and discussed theoretically. The result indicates that the SDAS is closely related to the solute microsegregation. With larger surface solute concentration differences between the coarse dendritic arm and the fine dendritic arm, the SDAS is wider, and the driving coarsening energy is more.

关 键 词：二次枝晶间距 微观偏析 形核率 镁合金 

分 类 号：TG292[金属学及工艺—铸造]